The present invention relates generally to quality control systems used with packaging conveyors in factory environments. More particularly, the invention relates to an apparatus and method for determining whether a closed package actually contains the desired contents.
In the packaging of dry food products and the like, it is important to determine whether each box contains all of the desired contents. One approach used in industry to address this problem has been to weigh each closed package as it moves past a weighing station on a conveyor. If a particular package weighs less than a known threshold, it is assumed that all of the contents are not present. Appropriate action can then be taken, such as activation of an ejector mechanism to remove the defective product from the conveyor stream.
While prior art weighing systems have been generally effective, they are not without disadvantages. For example, many dry food products, such as rice or pasta, will contain small seasoning packets having a weight less than the variance of the weighing system or the variance of the weight of one or more of the major components in the package. In this case, a weighing system would be unable to distinguish between a package with or without the small packet. In addition, it is often difficult to weigh individual packages that are constantly moving in a high-speed conveyor system. Weighing techniques are also unable to determine the position of the packed contents without opening the package.
The present invention recognizes and addresses the foregoing disadvantages, and others of prior art constructions and methods. Accordingly, it is an object of the present invention to provide improvements in quality control techniques used with packaging conveyors.
It is a further object of the present invention to provide an apparatus and method for use in detecting the contents of a closed package.
It is an additional object of the present invention to provide an apparatus and method for detecting metallized containers in a closed package.
It is a more particular object of the present invention to provide an apparatus and method for detecting metallized containers in closed packages moving rapidly in a conveyor stream.
Some of these objects are achieved by providing an apparatus used in conjunction with a packaging conveyor to detect metallized objects in respective packages moving along a conveyor stream. The apparatus comprises at least one coil unit mounted in association with the packaging conveyor such that the respective packages pass adjacent thereto. Field generation circuitry is also provided, electrically connected to the coil unit. The field generation circuitry is operative to apply a signal to the coil unit for generating a magnetic field through which the respective packages will pass. Measurement circuitry is operative to measure electrical changes in the coil unit due to the metallized objects and produce an output indicative thereof.
Other objects of the present invention are achieved by a method of detecting metallized objects in a closed package. One step of the method involves generating a magnetic field having a predetermined frequency. Next, the closed package is passed through the magnetic field. A change in the magnetic field due to presence of the metallized object is then detected. An output signal is then produced, indicative of the change in the magnetic field. In exemplary methodology, the output signal may be compared to predetermined levels. The results of the comparison can then be signaled for further use or processing.
Still further objects of the present invention can be achieved by an apparatus for detection of a metallized object in a package. The apparatus comprises a pair of coil units mounted in parallel planes such that the packages can be passed therebetween. Field generation circuitry is also provided, electrically connected to the coil units. The field generation circuitry is operative to apply a signal thereto for generating a magnetic field in a region between the coil units. Measurement circuitry is operative to measure changes in an impedance of the coil units due to the metallized object.
Other objectives, features and aspects of the present invention are provided by various combinations and subcombinations of the disclosed elements, as well as methods of practicing same, which are discussed in greater detail below.